SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4794cf7211ef035c437142a23e3adb17a522b801ee105923a7943e1d9b6f47f' 
  AND token = 'BMX9WhrYzcfagymIXIijy+DlEsRby913vCsFhh4qzzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}